On December 17, 1903, two bicycle manufacturers from Dayton, Ohio, stood on a windy beach at Kitty Hawk, North Carolina, and tossed a coin. While the winner, Orville Wright, positioned himself inside a flimsy machine, made of wood and cloth, his brother Wilbur started up their homemade gasoline engine. Moments later, the rickety contraption rolled along a metal guide rail, then, as it gained speed, it left the ground and flew about ten feet above the sand for twelve seconds, covering a distance of 120 feet.

The age of flight had begun.

A new type of combat had also been born, though the world’s leading military establishments were not quick to see it. It wasn’t until 1909 that the first military airplane was flown; the Wright Military Flyer could hold two people and carry them aloft for an hour, at a speed of 40 miles per hour. The US Army used the airplanes for aerial reconnaissance.

Although the first workable airplane had been produced in the United States, however, the most advanced work in aeronautics was done in France. In the years immediately following the Wright brothers’ flight, so many airplanes were being designed and flown in France, by people like Alberto Samos-Dumont, Gabriel Voisin, Louis Bleriôt, and Henri Fabré, that most modern aeronautical terms (such as “fuselage”, “aileron” and “nacelle”) are of French origin.

On July 25, 1909, Bleriôt flew a Model XI version of his airplane across the English Channel from France to Britain, and military leaders around the world were forced to realize that, in future wars, not even an island surrounded by the world’s strongest Navy was immune to being reached by a potential enemy.

That future war was only five years away, and, though no one knew exactly when it would happen, everyone knew it was coming. France was still smarting from its defeat in the 1870 Franco-Prussian War, and was looking for a chance to regain its lost provinces of Alsace and Lorraine. The newly unified Germany wanted to build a global empire equal to France and Britain’s. The British, whose imperial interests had long been in conflict with France’s, now found themselves sharing a common interest with their former rival, as both France and Britain sought to prevent German gains at their expense. Germany’s ally, the Austro-Hungarian Empire, was wracked by ethnic strife and internal divisions—a situation that was watched carefully by Tsarist Russia, which had its own territorial ambitions in the Balkans.

The breaking point came on June 28, 1914, when a Serbian nationalist student shot and killed Franz Joseph Ferdinand, the heir to the throne of Austria-Hungary. With the support of Germany, Austria-Hungary attacked Serbia in retaliation. Russia, in turn, mobilized its army to defend Serbia, Germany then attacked France, and Britain sent military forces to defend its allies. Within weeks, the Central Powers, consisting of Germany and Austria-Hungary, faced off against the Triple Entente Allies, made up of France, Britain and Russia. It was the war that everyone expected, and that everyone had already been planning for. Both sides were confident of victory, and both sides assumed that the war would be over before Christmas.

The German war strategy, known as the Schlieffen Plan, called for a large German army to avoid French border defenses by charging around them through Belgium, then driving on Paris to take France out of the war. For the Central Powers, surrounded on both sides by the Entente, it was imperative that France be knocked out of the war quickly, before the Russian army could fully mobilize. With France defeated, the Germans could then turn their full military power against Tsarist Russia.

The invasion of Belgium took place in the first week of August 1914. By September, German troops were within thirty miles of Paris, and it seemed as if the defeat of France was imminent. On September 6, however, French observation planes detected a gap between two German armies, and, in the “Miracle of the Marne”, French and British troops poured into the gap and drove the Germans back over forty miles. Paris was saved. Within weeks, the German army dug itself in, constructing a string of defensive trenches that stretched, unbroken, from the Swiss border all the way across Europe to the English Channel. The French and British also dug their own trench system, which was, in most places, 200-300 yards from the German lines (at some places, though, such as the Vimy Ridge, the opposing trenches were less than 30 yards apart). Far from being a quick and easy victory, the “Great War” settled into a deadlocked stalemate that would last for four long bloody years.

The defensive trenches soon became intricate and complex, with two or three trenchlines, one behind the other, connected by shorter communications trenches. A typical trench was about seven feet deep and four feet wide. The sides of the trenches were reinforced with wooden planks, sandbags, or wire mesh. At the front of the trench, a parapet of sandbags was built up, with small gaps called “loopholes” which allowed soldiers to stand on a “firing step” and shoot at the enemy. At intervals, a firing position made of sandbags was also placed for a new weapon, the machine gun. Designed in the United States, the Maxim machine gun was used by both sides. With overlapping fields of fire, the machine guns could cover the entire front, even if some of them were knocked out. Extensive tangles of barbed wire prevented enemy troops from crossing the “No Man’s Land” between the opposing trenches. The Germans were particularly good at building “defenses in depth”, in which a second entire defensive network of trenches would be built a mile or two behind the first, allowing troops to regroup there and counterattack if the primary trench network were captured.

Sheltered within these extensive underground networks, the defender had an overwhelming advantage against any attacker. The Germans, who were in occupied territory, took a defensive strategy, digging in firmly to oppose British and French efforts to dislodge them. The Entente generals had no experience with this new kind of trench warfare, but, knowing that it was up to them to drive the Germans out, desperately resorted to massive “human wave” attacks, throwing thousands of troops across No Man’s Land to try to penetrate the German defenses. Usually, these attacks were preceded by a massive artillery bombardment, which was intended to destroy the German trenches and kill everyone in them, but which were instead ineffective against the German troops in their trenches and deep dugouts. In attack after attack, the British “tommies” and French “poilu” charged across the cratered shell-pocked landscape, only to be hung up on the barbed wire and mowed down by the German machine guns. The Germans tried to break the stalemate with poison gas, a tactic which was quickly adopted by the British and French. It didn’t help. On the first day of the massive British attack on the Somme in 1916, almost 20,000 soldiers were killed by German machine guns. Attack was followed by counter-attack. Even during “quiet” periods, some 5,000 men were killed every day, from snipers, reconnaissance raids, or random artillery shells. And through it all, the battle front never moved by more than a few hundred yards. It was slaughter on a scale that the world had never seen before.

The Entente generals needed all the help they could get to find a way through the German trenches. The first weapon they turned to was artillery. During the Franco-Prussian War just 40 years earlier, artillerymen were still using cannons. By 1914, though, artillery had developed into an extremely effective killer. The old cannons were limited by their recoil, which knocked the cannon out of position and necessitated re-aiming after each shot. The modern breech-loading howitzers of 1914, however, could absorb the recoil without moving, allowing gunners to consistently pound the same spot again and again. One problem remained, though. The old cannons were aimed entirely by sight. The new artillery, however, had such long ranges that the gunners often could not see where their shells were landing, making it impossible for them to adjust their fire for greater accuracy.

It was the French expertise in aeronautics that helped solve the problem, and the earliest stage of aerial warfare centered around reconnaissance and artillery spotting. Unarmed two-seater airplanes began to regularly fly over enemy trenches—the observer in the rear seat would photograph them and provide critical information for planning ground attacks, as well as giving advance warning of enemy troop movements and imminent attacks. Observation planes were also used as aerial artillery spotters, watching the shells fall and, using a wireless Morse code transmitter, advising gunners on corrections to their aim, allowing intense and accurate bombardments of enemy positions with pinpoint accuracy.

At first, aerial observation was a tranquil affair. Opposing pilots would often wave to each other as they passed by, each on the way to photograph the other’s trenches. It quickly became apparent, however, that it was a huge military advantage to prevent the other side from observing one’s trenches. Rear-seat observers soon began carrying pistols and rifles to take potshots at each other, and it wasn’t long before light machine guns (like the British Lewis gun) were mounted at the rear of the plane for the observer to use against enemy reconnaissance flights. By 1915, both sides began designing single-seat “scout” planes, which were specifically intended to seek out and shoot down enemy observation planes, and to defend their own spotters from enemy scouts. During the war, most aces scored the majority of their aerial victories over enemy two-seat observation planes. This was not simply because the spotter planes were slow, lumbering, easy targets, but also because they were the most important military targets in the air.

Before an effective aerial fighter plane could be produced, however, a puzzle had to be solved. The simplest way for a solitary pilot to aim his gun was to mount it in line with the fuselage of his airplane, thus allowing him to aim the gun accurately simply by pointing the airplane’s nose at the target. And since machine guns were prone to jamming and also held a limited amount of ammunition, they had to be physically within the pilot’s reach so they could be reloaded and, if necessary, unjammed. The best location for this was on the cowling directly in front of the cockpit.

This, however, presented an awkward problem – it put the machine gun directly in line with the whirring propeller, and any pilot who aimed and fired his machine gun at an enemy would be virtually certain to shoot off his own propeller.

The first pilot to come up with an effective solution was the Frenchman Roland Garros. Garros attached a light Hotchkiss machine gun to the front of his Morane monoplane, and to prevent it from shooting off his own propeller, he bolted two steel wedges to the back of the blades, deflecting any bullets that might hit them as he was firing. On April 1, 1915, Garros successfully shot down a German observation plane over British trenches. Later that day, another French pilot with a modified Morane, Jean Lavarre, also shot down a spotter plane.

Over the next week, Garros refined his tactics. Since his Morane airplane was slower than the German biplanes he was chasing, he learned to loiter above the altitude normally taken by the spotters, then, when they passed below him, dive on them from behind to attack before they could speed away. On April 11, Garros intercepted two German spotter planes and shot them both down. They were his fourth and fifth aerial victories, making Garros the first fighter ace in history.

Less than a week after achieving ace status, though, Garros developed engine trouble while flying over German trenches and was forced to land. Garros was held as a POW until he escaped in early 1918 and made his way back to France. After a refresher training to learn to handle the newer French fighters, Garros returned to combat. He was shot down and killed in October 1918, just a month before the war ended.

Garros’s captured Morane monoplane, meanwhile, was turned over to the Dutch aircraft designer Anthony Fokker, who was working for the Germans. Fokker examined the steel wedges Garros had attached to his propeller blades, and knew that they enabled his plane to fire through the propeller, but Fokker was already working on a better system. His “interruptor gear” used a pronged cam attached to the propeller shaft to push a metal rod attached to the machine gun mechanism, which inactivated the gun whenever a propeller blade was directly in front of the barrel. Although the pilot could fire the machine gun continuously, the cam would interrupt the fire whenever the propeller was in the way.

The interruptor gear system was incorporated into Fokker's new Eindekker monoplane, known as the E-1. Faster than the Morane, the Eindekker was superior to anything the Entente could put into the air. Its larger more powerful engine allowed it to carry a Spandau machine gun, which was more powerful than the Hotchkiss carried by Garros.

The E-1 was the first purpose-built fighter plane, and two Eindekkers were placed immediately in combat, one each to pilots Max Immelman and Oswald von Boelcke. On August 1, 1915, a flight of British BE2c bomber/observer planes attacked the German airfield at Douai, and Immelman and Boelcke took off in their Fokkers to intercept. Boelcke's gun jammed and he was forced to land, but Immelman shot down one of the BE2c's and damaged another.

For the rest of 1915, Immelman and Boelcke carried on a friendly rivalry, with each matching the other’s score. By October, both had scored five aerial victories and reached “ace” status. On January 12, 1916, both aces scored their eighth victories, and both were awarded the Pour le Merite, the coveted military medal known informally as “The Blue Max”. Throughout the first half of 1916, improved models of the Eindekker were shooting down so many Entente spotter planes that French and British fliers referred to the period as “The Fokker Scourge”.

Immelman was killed in June 1916, after scoring a total of 15 aerial victories. He was shot down in combat with a number of British Fe2b’s, though there are some indications that his interruptor gear had malfunctioned and shot off his own propeller.

Although Immelman had gotten most of the attention from the German press (he was known as “The Eagle of Lille”), it was Boelcke who made the most lasting contribution to aerial combat. A skilled tactician, Boelcke was also a masterful organizer and, more importantly, an instructor. His observations on aerial combat and organization, known as “Boelcke’s Dicta”, are still taught today to modern jet fighter pilots.